The operation of internal combustion engines with alternative fuels may result in strong wear of those components of the fuel system that are in contact with the fuel. Specifically, fuel systems may be affected by the increased cavitation activity caused by an increased water content of alternative fuels.
Additionally to the operation with alternative fuels, fuel systems may also be configured for interchanging operation with conventional fuels, including diesel fuels (DFO), light fuel oil (LFO), heavy fuel oil (HFO), or low and high sulphur fuels. Thus, generally, the fuel systems may become in contact with a large variety of types of fuels at various temperatures and pressures.
Fuel systems may comprise high pressure fuel pumps using a plunger as disclosed, for example, in EP 2 339 166 A1. FR 1 567 479A discloses further a step-wise recessed fuel control region on the plunger's surface. High pressure pumps may be used for marine engines, construction machine engines, or other large internal combustion engines.
Fuel systems may further comprise various high pressure components such as a high pressure pump connector, short high pressure pipes, and long high pressure pipes. Finally, the fuel system may comprise an injection system.
Alternative fuels include, for example, first generation biofuels (e.g. palm oil, canola oil, oils based on animal fat) and second generation biofuels (e.g. oils made of non food corps, i.e. waste biomass). Examples of second generation biofuel include “pyrolysis oils” obtained from the pyrolysis of, e.g., wood or agricultural wastes, such as the stalks of wheat or corn, grass, wood, wood shavings, grapes, and sugar cane. In particular, alternative fuels may have an increased water content of, for example, <26% by volume as it may be the case for pyrolysis oils and ethanol based fuels as described in the European patent application EP 12 157 275.4 filed on 28 Feb. 2012 by Caterpillar Motoren GmbH & Co. KG.
The chemical composition and the physical properties of alternative fuels such as pyrolysis oils and ethanol based fuels and of low sulphur fuels can differ significantly from those of DFO, LFO, and HFO, in particular with respect to the high content of water and oxygen, the acidic pH-value in the range around, e.g., 2 to 3.5, and the rather low heating value. Moreover, alternative fuels and low sulphur fuels can have poor or completely missing lubrication properties and usually comprise small size particles in the range of, e.g., 0.1-5 μm. Also the temperature of use is generally lower for alternative fuels and low sulphur fuels than for, e.g., HFO. For example, a temperature of use of 60° C. is common for pyrolysis oils to provide a viscosity, which is suitable for fuels to be injected into a combustion chamber of an engine.
Due to the chemical composition and the physical properties of alternative fuels, alternative fuels may have an increased cavitation and corrosion activity and increase the wear of the components of the fuel system.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.